DNA and RNA Structure and Function

Primer sequence

provides a starting point and is added with complementary RNA nucleotides

Termination signals

repeated nucleotide sequences in the DNA template which results in the freeeing of the mRNA transcript

Leading Strand

the DNA strand that is continuously made up to the replication fork

Replication Forks

the areas where the double helix separates

tRNA charging

the attachment of a tRNA to its appropriate amino acid is called ___________

4 types of nitrogenous bases in DNA

(A) Adenine (C) Cytosine (G) Guanine (T) Thymine

how is gene expression expressed in prokaryotic cells

- Is is accomplished via regulation of DNA transcription into RNA - Is mostly done at the transcription level

Step 3 of prokaryotic protein synthesis

- Termination - Stop codon (UAA, UAG, UGA)

RNA polymerase

- an enzyme that adds nucleotides by temporarily pairing with DNA. - DNA unwinds prior to and rewinds after.

Step 2 of prokaryotic protein synthesis

- elongation - the basics are the same as the elongation step of eukaryotes - "A" site binds incoming tRNAs - "P" site binds tRNAs whose polypeptide chain yet has not been dissociated from their corresponding tRNA - "E" site releases dissociated tRNA

Step 1 of Prokaryotic Protein synthesis

- initiation - tRNA interacts with the start codon and links ot a special form of methionine (usaually removed from the polypeptide once translation is complete)

introns

- intervening sequences - Noncoding segments of nucleic acid that lie between coding sequences. - removed while pre-mRNA is still in the nucleous

Step 1 of eukaryotic mRNA processing

- it gets coated with stablizing proteins to prevent degredation - occurs while it is still made

E.Coli (representative or prokaryotes) initiation stage of protein synthesis consists of

- small subunit of ribosome - mRNA template - three initiation factors - a special inititator tRNA

There is/are ____ start codon(s) labeled _____, whose purpose is to ____ and resides ______

1 AUG Initiate translation and specifying the amino acid methionine Resides at the 5' end of the mRNA

DNA Replication Process

1. DNA unwinds at origin of replication 2. New bases are added to the parental strand of DNA and the new strand is pieced together 3. Primers are replace with DNA nucleotides and the backbone sealed by DNA ligase

There is/are _____ stop codons and they are ______, ______, and ________. Whose purpose is to _____.

3 UAG, UGA, UAA Terminate protein synthesis

Much like mRNA synthesis, protein synthesis consist of ___ stages which are____

3 stages (similar to mRNA) Initiation, elongation, and termination

DNA composition

3' up and 5' up are the outsides and the pairings are what connects them

Escherichia Coli base pairs

4.6 million base pairs ~1000 nucleotides are added per second

Escherichia coli within Prokaryotes

4.6 million base pairs that would extend 1.6mm and must be supercoiled

What direction is DNA synthesized

5' to 3' (5-carbon sugar)

Poly-A tail

50 - 250 Adenine nucleotides added to the 3' end of a pre-mRNA.

How many combinations are there using the three-nucleotide code

64 (4x4x4)

AT and CG bondage

AT 2 hydrogen bonds CG 3 hydrogen bonds

of the 4 nitrogen bases of DNA which are double-ringed purines and which are single-ringed

Adenine and Guanine (the ones eding in NINE) are double Cytosine and Thymine (ending only in INE) are single

what are the complementary base pairs of DNA

Adenine-Thymine (AT) Guanine-Cytosine (CG)

Helicase

An enzyme that unwinds DNA

what is the difference between DNA and RNA 5-carbon sugar

DNA - deoxyribose has a hydrogen atom at the 2' RNA - ribose which has a hydroxyl group at 2'

Two types of nucleic acids

DNA and RNA

In prokaryotic organisms, why does translation and transcription occur simultaneously

Because prokaryotic organisms lack cell nuclei

Central Dogma

DNA encodes RNA which encodes proteins

Explain the protein synthesis process in Eukaryotes

DNA is inside cell's nucleous and is transcribed into mRNA there and then transported out of the nucleous into the cytoplasm via tRNA

Initiation Stage or DNA replication

DNA is made available to the proteins and enzymes

DNA packing in Eukaryotes

DNA is wrapped around histones and become nucleosomes. Nucleosomesare linke to the next via a short piece of DNA without the histones. The nucleosomes are stacked on each other to form a 30nm wide chromatin fiber. This fiber is coiled to form a thicker more compact structure 700nm wide

What replaces the RNA primer

DNA nucleotides

Elongation Stage of DNA Replication

DNA nucleotides are added to the 3' end of the DNA template (DNA polymerase)

Transcription Bubble

DNA region of unwinding during initation

What is a Nucleotide comprised of

Deoxyribose (5-carbon sugar) Phosphate group Nitrogen Base

Where are ribosomes located

P - cytoplasm E - cytoplasm and endoplasmic reticulum

Nucleotide Excision Repair

Enzymes cut out incorrect bases and fill in correct bases

In Eukaryotes when does gene expression occur

Epigenetic level Transcription level Post-transcription level Transitional level Post-transitional level

Lac Operon

In E coli, consists of the three lactase digesting genes and their associated promoter and operator.

3 stages of Eukaryote DNA replication

Initiation Elongation Termination

The area between the Promoter and the three genes

Is where the operator is resides

Building Blocks of DNA

Nucleotides

exons

Protein-coding sequences signifies that they are expressed

Origins of Replication

Sites where the replication of a DNA molecule begins.

Step 3 of eukaryotic mRNA processing

Termination

Mismatch Repair

The cellular process that uses special enzymes to fix incorrectly paired nucleotides.

Telomeres

The ends of chromosomes

Gene Expression

The process of turning on a gene to produce RNA and protein

Template strand

The strand of DNA used in transcription to produce mRNA

Lagging Strand

The strand with the Okazaki Fragments

How does eukaryote protein synthesis differ from prokaryotes

Transcription and Translation occur at the same time in Prokaryotes in the same place where as Eukaryotes Transcription and Translation occur in two different place (separated by nuc mem)

Promoter

a region of DNA that initiates transcription of a particular gene

DNA for Prokaryotes

a single, circular chromosome found in the nueloid which is located within the cytoplasm

DNA polymerase

adds DNA nucleotides to the DNA's backbone

Step 2 of eukaryotic mRNA processing

after elongation occurs, 200 adenine residues are added to the 3' end - the poly-A-tail

telomerase

an enzyme that helps elongate the lagging strand so the Nucleotides can be added Not present in Adult Somatic cells associated with aging as the telomeres are continue to shortened

Okazaki Fragments

are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA

Large subunit of a ribosome

binds tRNAs together sequentually

Lac Operon repressor protein

binds to the operator to prevent RNA polymerase

mRNA template

converts nucleotide-based genetic information into a protein product

mRNA

messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosome

Translation requires . . .

input for mRNA ribosomes tRNAs various enzymatic factors

semiconservative replication

each new DNA molecule consists of one new strand and one old strand

DNA ligase

enzyme that links DNA fragments together

What does translation involve

it involves the decoding of the mRNA message into a polypeptide product (proteins)

Which of the 5-carbon sugar is the phosphate group attached

it is attached to the 5' carbon of one nucleotide and the 3' carbon of the next nucleotide

Which nitrogen base is missing from RNA that is present in DNA

it is missing Thymine however it contains uracil (U)

Small subunit of a ribosome

it is responsible for binding the mRNA template

what do tRNAs need to function

it needs to have specific amino acids bonded to it

Non-template strand

mRNA similarily identical except RNA uses Uracil (U) instead of Thymine (T)

Eukaryotic RNA Processing

mRNA's must undergo several steps which make it last longer than prokaryotic mRNA (5sec)

Which RNA molecule are involved in producing proteins of the DNA code

mRNA/tRNA/rRNA

What is a ribosome

macromolecule made of structural and catalytic rRNAs and many polypeptides

Differences between Prokaryotes and Eukaryotes

point of origin (P single/ E many) Rate of replication (P 1000ps / E 50-100) chromosome structure (P circular / E linear) Telomerase (P none / E present)

splicing

process of removing introns and rejoining exons of pre-mRNA's

Genetic Code

the relationship between a nucleotide codon and its amino acid

What is the "backbone" of DNA

the sugar-phosphate group

Prokaryotes termination signal

the transcription would have been used to make copies of the protein which DNA demands because it happens concurrently

Number of tRNAs w/n a cytoplasm

there are 40 - 60 w/n a cytoplasm

What is the bond for which the phosphate and sugar group connected

they are connected via a covalent bond

where are replication forks formed

they are formed at the origin of replication

Triplet Codon

three nucleotide sequence on mRNA that codes for specific amino acids

tRNA

type of RNA that carries each amino acid to a ribosome during protein synthesis